The trend in secondary biology is to use living material in so far as it is possible. Biology instruction, as it has advanced beyond the descriptive level, has included more projects requiring living animals. The local collecting and culturing of some of these organisms adds just that much more biological experience to the course

Christensen, Cameron L.

University of Northern Iowa

Iowa Science Teachers Journal Volume 2 Number 2 Article 11 1964 Collection and Culture of Lower Animal Forms Cameron L. Christensen Follow this and additional works at: https://scholarworks.uni.edu/istj  Part of the Science and Mathematics Education Commons Let us know how access to this document benefits you Copyright © Copyright 1964 by the Iowa Academy of Science Recommended Citation Christensen, Cameron L. (1964) "Collection and Culture of Lower Animal Forms," Iowa Science Teachers Journal: Vol. 2 : No. 2 , Article 11. Available at: https://scholarworks.uni.edu/istj/vol2/iss2/11 This Article is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Iowa Science Teachers Journal by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu. 38 DECEMBER, 1964 Collection and Culture of Lower Animal Forms CAME RON L. CHRISTENSEN Rockwell City The trend in secondary biology is to use living material in so far as it is possible. Biology instruction, as it has advanced be-yond the descrip-tive level, has in-cluded more pro-jects reg u i r i n g living animals. The local collecting and culturing of some of these organisms adds j u s t t h a t much more biologi-cal experience to Christensen the course. The common and most used method of collecting the less mobile aquatic organisms has been to obtain organic material from the bottom of a body of water. To find what has been collect-ed, the debris was washed or scraped into a container of clean pond water . This method requires a great deal of work and time. The results a1·e, at times, not too rewarding. The collecting of "lower" aquatic organisms is made much easier by the placing of microscope slides or glass plates directly into the habitat of these animals. This can be accomplish-ed by placing slides in an old slide box and weighting it so it can be submerg-ed. In time, the organisms will attach themselves to the slid s and can thus be studied directly without the need of being transferred several times. This method is neither new nor was it developed by the author. It's use has never been wide-spread. Slide box col-lections have been used for many years by scientists at the Iowa Lake-side Laboratories and elsewhere for collections of aquatic insect larvae, hy-dra, sponges, and many of the less mobile protozoa. It is simple and fool-proof enough that students can do much of the collecting themselves. An interesting result is that the sciE>nc•f> student becomes a scientist complete with research problems to be develop-ed. The advantage of having the stud-ents doing the collecting is two-fold. First, the pupil collecting, identifying and observing the life processes of or-ganisms is carrying on scientific stud-ies. The students tend to develop a scientific way of thinking and scienti-fic attitudes as they record and write up their observations. Second, the idea that organisms such as suctoria, sponges and hydra are exotic creat-ures that must be imported from far away places does not form. The stud-ent thus develops confidence and inter-est in science as he finds he is able, with only limited knowledge to carry on scientific .study in his own locality with a minimum of outside help. The William Schmidt, biology instructor at E ll sworth Junior College, ho ld,s a slide box containing several p a ir of glass slides. With the cover in place, and a weight at -tached, the e ntire assembly can be sub -merged for several days in a lake or ,.: trea m . Examination of the slides after recovery reveals a large number of pro-tozoa , gveen an d blue-g-reen algae, and diatom s. following materials are needed : I . Pails, buckets and cans. ·> A roll of strong cord. ::. HP,Jtvy oh.ie<'t. ~uitnhle for we ig:hts ( th,· DECEMBER, 1964 city dump is fu11 of such objects) 4. Slide cases* (the slots must be widened so that two slides can be inserted in each one). *Suitable slide holders can be easily constructed in the school shop or home workshop. If commercial slide boxes are to be used, the bottom should be taken out so that the current may carry through it. It is also advisable to nail the box as glue has a tendency to let Tim Kleemeier, Dave Wheatley, and Lynn O'Leary, biology atudents from Rockwell City, recover a aubmerged sl'ide case from North Twin Lake. The slide case and the g lau slides in it are placed in a contain e r of lake water. In this way organisms atta ched to the slides can be transported to the stud y area or back to the classroom. 39 go. A hole drilled in the ends of the box will make it possible to attach the weight and a cord for supporting it upright in the water. The preparation of the slide box from this point is simple. Secure a-bout sixteen slides (eight pair) and with rubber bands, bind each pair tightly together. Next, place the eight pair into the slide box and hold them in place by use of more rubber bands. A strong cord of some length may be attached at one End of the box and the weight at the other. Place the slide holder near the botr tom of an open body of water. This may be a lake, pond, river or even a dredge ditch. Secure the retaining cord to any handy object: a tree limb, bridge or fence. Leave the slides submerged for a On-the- ·pot examinations of organisms collected by the slide box method , and by other means can be made in the field. The tail gate of a station wagon serves as a laboratory bench. period of from one day to a week. If the time is too short, the organisms wil not have attached themselves in sufficient numbers to study. If the time is too great, the slides will have accumulated so much sediment that nothing else can be observed. The time factor will have to be determin-ed for each location. Retrieve the slides in the holder and place in a container filled with 40 water from the same body of water. The shock of environment change is reduced by this procedure and the death rate is slower and not so great. Place enough of the collected water to cover a slide in a petri dish and place the lo-wer microscope slide of the exposed pair in the dish. The up-per slide of the pair commonly has so much sediment affixed to it that little can be observed so it should be dis-carded. The slide may now be observed with a hand lens, a wide field, or com-pound microscope. It is not advisable to submerge lenses into the water, but no apparent damage is evident if they are cleaned and dried immediate-ly after use. The use of slides for collecting will result in a great diversification of organisms. It is advisable to have a large number of keys available for student use. The book, Taxonomic Keys To The Common Animals Of The North Central States, by Eddy and Hodson will suffice in most cases. To limit the length of this paper only a few will be mentioned. The "tested" Sarcodina and the Suctoria, classes of Proto~oa, show up commonly on these slides. If spring studies are made, small fresh water sponges are in evidence but are some~ times difficult to recognize unless the \. observer is trained to recognize them. Should the slides be placed in shady slow-moving water green, brown, and black hydra can be found attached to the slides. Insect larvae will be found at times . The caddicefly in his self-built case draws student interest. A check of the work listed in the references will off er culture methods for the more common organisms col-lected. Some are difficult or almost impossible to maintain for long per-iods of time. 1. Sarcodina and Suctoria Fill a gallon jar with pond water, con-taining some green plant material, and place t.he slides containing these protozoa at the bottom. This aquarium should be placed where it will receive light but never direct sunlight. The urvival time under DECEMBER, 1964 these conditions ranges from one to twQ months. Z. Fresh W-ater Sponges There is no good method to maintain actiive cultures of sponges. They will last for a week or two if left in the water where they were collected or placed in a clean balanced aquaria. balanced aquarium. The most accepted method to maintain hydra is in pond water containing green plants and a culture of Daphnia. Should a large number be collected they can be maintained with no consideration for three months by placing them in a small covered container of pond water on t he bottom shelf of the refrigerator. 4. Insect Larvae They will grow and even develop to maturity in a well-balanced la:rge (5 or more gallon) aquarium ii Daphnia or other fre sh-water crustaceans are present in suf -ficient number. The collecting and culturing of aquatic organisms in high schools has often been neglected because of the large amount of time and effort need-ed, and the poor results obtained. It is hoped that this simpler and some-what surer method will result in more diversified use of these organ-isms in secondary biology studies. REFERENCES Ed dy a nd Hodson- Taxonomic Keys to the Common Animals of the North Central States. Burgess Publishing Co., 1962. Miller and Blaydes-Methods and Materi.al11 for Teaching the Biological Sciences. McGraw-Hill Book Co., 1962. The Care of Protozoan Cultures in the Laboratory, No. 4. The Care of Living Insects in the School Laboratory, No. 34. The Fresh Water Hydras, No. 39. General Biological Supply House, Chicago, Ill. Needham, J. G.-Culture Methods For In-vertebrate Animals. Comstock Publish-ing Assoc., Inc., 1937. The unsleeping eye of science also has discovered that neither the tapeworm nor the hookworm has a heart. The largest infant ever born in this world is the calf of a blue whale. At birth, the whale calf measures up to 25 feet long and weighs several tons. In contrast, a polar bear c.ub weighs about a pound upon emergence from its mother, and can be cuddled in a woman's hand . 

Collection and Culture of Lower Animal Forms

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